Creep, Steel

A generalisation of the Wilshire–Scharning methodology to creep life prediction with application to 1Cr–1Mo–0.25 V rotor steel

Wilshire–Scharning have recently developed a new methodology that has been demonstrated to deliver accurate longer term creep life predictions, and so offers the prospect of cost-effective acquisition of long-term creep design data. This methodology differs from existing approaches to creep life prediction by normalising the applied stress through the appropriate tensile strength. This article develops a generalisation of this Wilshire–Scharning model that has the potential … Continue reading A generalisation of the Wilshire–Scharning methodology to creep life prediction with application to 1Cr–1Mo–0.25 V rotor steel

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Steel

Use of partial least squares for identifying the effect of through process variables on some of the magnetic properties (permeability) of grain oriented electrical steel

As there are a large number of process variables involved in manufacturing grain oriented electrical steel, partial least squares (PLS) was used to study the influence of these process parameters on some magnetic properties and in particular on permeability. It was found that a model containing just two PLS components provided an adequate best fit to the process data with the most important variables being … Continue reading Use of partial least squares for identifying the effect of through process variables on some of the magnetic properties (permeability) of grain oriented electrical steel

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Steel

An alternative approach to estimating the parameters of a generalised Grey Verhulst model: An application to steel intensity of use in the UK

Being able to forecast time series accurately has been quite a popular subject for researchers both in the past and at present. However, researchers have resorted to various forecasting models that have different mathematical backgrounds, such as statistical time series models, causal econometric models, artificial neural networks, fuzzy predictors, evolutionary and genetic algorithms. In this paper, a brief review of a relatively new approach, known … Continue reading An alternative approach to estimating the parameters of a generalised Grey Verhulst model: An application to steel intensity of use in the UK

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Creep, Titanium

Alpha-Case Kinetics and Surface Crack Growth in the High-Temperature Alloy TIMETAL 834 Under Creep Conditions

Investigations of Timetal 834 crept specimens showed that a uniform alpha-case layer was developed at the surfaces of all specimens tested in air at 823 K to 923 K (550 °C to 650 °C). The formation of this alpha-case was a result of the inward diffusion of oxygen, which is an alpha stabilizer, and other elements promoting the transformation of the beta matrix into an alpha phase and, thus, … Continue reading Alpha-Case Kinetics and Surface Crack Growth in the High-Temperature Alloy TIMETAL 834 Under Creep Conditions

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Environmental, Fatigue, Nickel, Peening, Superalloys

Factors affecting the corrosion fatigue life in nickel based superalloys for disc applications

The nickel based superalloy 720Li is employed in the gas turbine due to its mechanical performance at elevated temperature. A comprehensive assessment of the materials behaviour under representative service conditions is reported to address the drive for ever increasing temperatures and more arduous environmental exposure. Fatigue experiments have been performed in an air and air/SOx environment at 700 ∘C containing a mixed salt as a contaminant. … Continue reading Factors affecting the corrosion fatigue life in nickel based superalloys for disc applications

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Steel, Tensile

Development of a high temperature flow stress model for AerMet 100 covering several orders of magnitude of strain rate

Constant strain rate, constant velocity and Hopkinson Pressure Bar compression tests were carried out on AerMet 100 martensitic steel between 1130 °C and 1250 °C spanning strain rates from 0.01 s−1 to 4000 s−1. The results were used to generate a predictive flow stress model over the entire range of test conditions. The effect of initial austenite grain size on flow stress was found to follow the Hall–Petch relationship. … Continue reading Development of a high temperature flow stress model for AerMet 100 covering several orders of magnitude of strain rate

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Steel, Titanium

Insights into microstructural interfaces in aerospace alloys characterised by atom probe tomography

Atom probe tomography (APT) is becoming increasingly applied to understand the relationship between the structure and composition of new alloys at the micro- and nanoscale and their physical properties. Here, we use APT datasets from two modern aerospace alloys to highlight the detailed information available from APT analysis, along with potential pitfalls that can affect data interpretation. The interface between two phases in a Ti–6Al–4V … Continue reading Insights into microstructural interfaces in aerospace alloys characterised by atom probe tomography

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Fatigue, Nickel, Peening, Superalloys

Influence of shot peening on high-temperaturecorrosion and corrosion-fatigue of nickel basedsuperalloy 720Li

High-temperature corrosion fatigue, a combination of corrosion with a fatigue cycle, is an emerging generic issue affecting power generation and aero gas turbine engines and has the potential to limit component life. Historically, surface treatments, such as shot peening have been used to improve component life and have been optimised for fatigue response. Research into optimisation of shot peening techniques for hot corrosion and high-temperature … Continue reading Influence of shot peening on high-temperaturecorrosion and corrosion-fatigue of nickel basedsuperalloy 720Li

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Nickel, Superalloys

Microstructural evolution of a delta containing nickel-base superalloy during heat treatment and isothermal forging

The next generation of aerospace gas turbine engines need to operate at higher temperatures and stresses to improve their efficiency and reduce emissions. These operating conditions are beyond the capability of existing nickel-base superalloys, requiring the development of new high temperature materials. Controlling the microstructures of these new materials is key to obtaining the required properties and, therefore, it is critical to understand how these … Continue reading Microstructural evolution of a delta containing nickel-base superalloy during heat treatment and isothermal forging

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Nickel, Superalloys

Characterisation of an Advanced Nickel Based Superalloy Post Cold Work by Swaging

Cylindrical bars of the advanced nickel based superalloy RR1000 were subjected to swaging to induce approximately 30% cold work. Grain size analysis demonstrated a distinct modification to the microstructure whilst electron back scattered diffraction (EBSD) measurements confirmed the evolution of a relatively strong <111> texture parallel with the longitudinal bar axis. Intragranular strain damage was identified. The effects of the swaging on bulk mechanical properties … Continue reading Characterisation of an Advanced Nickel Based Superalloy Post Cold Work by Swaging

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